1. Field of the Invention
This invention relates to a non-stop automatic toll collection system for automatically collecting a toll charge from vehicles traveling on a toll road without requiring the vehicles to stop.
2. Description of the Prior Art
Conventionally, magnetic card toll collection systems have been used on toll roads. These systems are described in detail in for example, "Magnetic Card Toll Collection System", the Toshiba Review (Vol.40, No.3), 1985, p.189-p.192, or in "Magnetic Ticket Type Toll-Collection System", Mitsubishi Heavy Industries Technical Report Vol.22, No.6(1985-11), p.127-p.132.
In these conventional systems, when a vehicle left an ordinary road to travel on a toll road, or conversely, when a vehicle left the toll road to travel on an ordinary road, it had to make a temporary stop at a toll station to receive a travel ticket or pay a toll fee. This situation led to vehicles queuing in front of the toll station. Hence, non-stop automatic toll collection systems have been proposed wherein fee collection is made without vehicles having to stop.
Such systems are described in detail in, for example, "Need and Technology Development for Traffic Management System of Expressway", Mitsubishi Heavy Industries Technical Report Vol.32, No.4(1995-7), p.264-p.267, "The Fight for Leadership in Japan/U.S./Europe Regarding "Signaling" from Roads to Vehicles", NIKKEI BUSINESS, Jan. 13, 1995, p.155-p.158, and Published Translation of PCT Filed Patent No. Hei 5-508492 (Koho), "Electronic Vehicle Toll Collection Device and Method". A particularly full description appears in Published Translation of PCT Filed Patent No. Hei 5-508492 (Koho).
In Japan, non-stop automatic toll collection systems are being jointly developed by the Government and the private sector, and according to an article which appeared in the Yomiuri Shinbun of Oct. 29, 1996 (morning edition, p.26-p.27), plans are under way with a view to the commercial use of such systems by fiscal year 1999.
According to Nikkei Mukku (published Nov. 6, 1995), "Everything about ITS", systems of the type described in the above patent (Koho) are already in use in some countries, e.g. in Europe (Germany, Norway, etc., p.168-p.171), U.S.A., (p.140-p.143) and South-East Asia (Malaysia, Singapore, etc., p.190-p.191).
FIG. 1 shows the outlines of a conventional nonstop toll collection system.
A toll collection area 10 for receiving tariffs by radio is defined by an entry sensor 12 and exit sensor 14. The constructions of the entry sensor 12 and exit sensor 14 are identical, these sensors detecting the passage of a body traveling within approximately 2 m from a road surface. The entry sensor 12 is situated at the front end of the collection area 10, while the exit sensor 14 is arranged at the rear end of the toll collection area 10.
When a vehicle 16 enters the area 10 in a direction shown by an arrow Y in the figure, its front end is detected by the entry sensor 12. Communication then takes place between a vehicle-mounted device 18 mounted on the vehicle 16 and an antenna 20, and a tariff is collected.
However in this conventional system, due to the characteristics of radio waves, the antenna 20 may pick up radio waves from outside the toll collection area 10. This is due to scattering of radio waves when there is a radio wave leakage area 22 due to the installation position of the antenna 20, as shown in FIG. 1. It may also occur due to, for example, the entry and exit sensors 12, 14, ticket vending machines for vehicles not equipped with the vehicle-mounted device 18 or tariff boxes where there are collection personnel.
Consequently, there was a problem in that communication sometimes took place with vehicle-mounted devices 18 outside the collection area.
There was also a problem in that mistakes were sometimes made in distinguishing vehicles carrying the vehicle-mounted device 18 (Electronic Toll Collection Vehicles, referred to hereafter as ETC vehicles) and vehicles not carrying the vehicle-mounted device 18 (non-ETC vehicles).
For example, when a non-ETC vehicle enters the toll collection area 10 alone, there is no information exchange by radio, so it may be assumed that this vehicle is a non-ETC vehicle. However, when an ETC vehicle and a non-ETC vehicle are traveling close together, it may occur that the ETC vehicle is incorrectly determined to be a non-ETC vehicle.
An example of this is seen in FIG. 2, when the ETC vehicle 16 is following a non-ETC vehicle 24 in front of it, and is incorrectly determined to be a non-ETC vehicle. In this case, when the non-ETC vehicle 24 in front enters the toll collection area 10, communication is established between the antenna 20 and the vehicle-mounted device 18 of the ETC vehicle 16 behind due to the existence of the radio wave leakage area 22, so it is incorrectly determined that such communication has taken place with the non-ETC vehicle 24. As a result, a tariff is not collected from the non-ETC vehicle 24. Moreover, since the vehicle-mounted device 18 on the ETC vehicle 16 determines that communication has terminated, no further exchange of information occurs with the antenna 20 even when the vehicle enters the toll collection area 10, so the ETC vehicle 16 is then determined to be a non-ETC vehicle.
The ETC vehicle 16 therefore has to pay the fee for the non-ETC vehicle 24 which was traveling in front of it, and also has to pay the fee directly to a member of the toll collecting personnel.